freebsd-dev/crypto/openssh/ssh-pkcs11-helper.c

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/* $OpenBSD: ssh-pkcs11-helper.c,v 1.14 2018/01/08 15:18:46 markus Exp $ */
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/*
* Copyright (c) 2010 Markus Friedl. All rights reserved.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include "openbsd-compat/sys-queue.h"
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "xmalloc.h"
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#include "sshbuf.h"
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#include "log.h"
#include "misc.h"
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#include "sshkey.h"
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#include "authfd.h"
#include "ssh-pkcs11.h"
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#include "ssherr.h"
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#ifdef ENABLE_PKCS11
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/* borrows code from sftp-server and ssh-agent */
struct pkcs11_keyinfo {
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struct sshkey *key;
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char *providername;
TAILQ_ENTRY(pkcs11_keyinfo) next;
};
TAILQ_HEAD(, pkcs11_keyinfo) pkcs11_keylist;
#define MAX_MSG_LENGTH 10240 /*XXX*/
/* input and output queue */
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struct sshbuf *iqueue;
struct sshbuf *oqueue;
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static void
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add_key(struct sshkey *k, char *name)
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{
struct pkcs11_keyinfo *ki;
ki = xcalloc(1, sizeof(*ki));
ki->providername = xstrdup(name);
ki->key = k;
TAILQ_INSERT_TAIL(&pkcs11_keylist, ki, next);
}
static void
del_keys_by_name(char *name)
{
struct pkcs11_keyinfo *ki, *nxt;
for (ki = TAILQ_FIRST(&pkcs11_keylist); ki; ki = nxt) {
nxt = TAILQ_NEXT(ki, next);
if (!strcmp(ki->providername, name)) {
TAILQ_REMOVE(&pkcs11_keylist, ki, next);
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free(ki->providername);
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sshkey_free(ki->key);
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free(ki);
}
}
}
/* lookup matching 'private' key */
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static struct sshkey *
lookup_key(struct sshkey *k)
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{
struct pkcs11_keyinfo *ki;
TAILQ_FOREACH(ki, &pkcs11_keylist, next) {
debug("check %p %s", ki, ki->providername);
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if (sshkey_equal(k, ki->key))
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return (ki->key);
}
return (NULL);
}
static void
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send_msg(struct sshbuf *m)
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{
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int r;
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if ((r = sshbuf_put_stringb(oqueue, m)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
static void
process_add(void)
{
char *name, *pin;
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struct sshkey **keys;
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int r, i, nkeys;
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u_char *blob;
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size_t blen;
struct sshbuf *msg;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
(r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if ((nkeys = pkcs11_add_provider(name, pin, &keys)) > 0) {
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if ((r = sshbuf_put_u8(msg,
SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
(r = sshbuf_put_u32(msg, nkeys)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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for (i = 0; i < nkeys; i++) {
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if ((r = sshkey_to_blob(keys[i], &blob, &blen)) != 0) {
debug("%s: sshkey_to_blob: %s",
__func__, ssh_err(r));
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continue;
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}
if ((r = sshbuf_put_string(msg, blob, blen)) != 0 ||
(r = sshbuf_put_cstring(msg, name)) != 0)
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
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free(blob);
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add_key(keys[i], name);
}
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free(keys);
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} else {
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if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
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free(pin);
free(name);
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send_msg(msg);
sshbuf_free(msg);
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}
static void
process_del(void)
{
char *name, *pin;
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struct sshbuf *msg;
int r;
if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_get_cstring(iqueue, &name, NULL)) != 0 ||
(r = sshbuf_get_cstring(iqueue, &pin, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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del_keys_by_name(name);
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if ((r = sshbuf_put_u8(msg, pkcs11_del_provider(name) == 0 ?
SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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free(pin);
free(name);
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send_msg(msg);
sshbuf_free(msg);
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}
static void
process_sign(void)
{
u_char *blob, *data, *signature = NULL;
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size_t blen, dlen, slen = 0;
int r, ok = -1;
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struct sshkey *key, *found;
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struct sshbuf *msg;
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/* XXX support SHA2 signature flags */
if ((r = sshbuf_get_string(iqueue, &blob, &blen)) != 0 ||
(r = sshbuf_get_string(iqueue, &data, &dlen)) != 0 ||
(r = sshbuf_get_u32(iqueue, NULL)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
error("%s: sshkey_from_blob: %s", __func__, ssh_err(r));
else {
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if ((found = lookup_key(key)) != NULL) {
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#ifdef WITH_OPENSSL
int ret;
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slen = RSA_size(key->rsa);
signature = xmalloc(slen);
if ((ret = RSA_private_encrypt(dlen, data, signature,
found->rsa, RSA_PKCS1_PADDING)) != -1) {
slen = ret;
ok = 0;
}
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#endif /* WITH_OPENSSL */
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}
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sshkey_free(key);
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}
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if ((msg = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
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if (ok == 0) {
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if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
(r = sshbuf_put_string(msg, signature, slen)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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} else {
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if ((r = sshbuf_put_u8(msg, SSH2_AGENT_FAILURE)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
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free(data);
free(blob);
free(signature);
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send_msg(msg);
sshbuf_free(msg);
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}
static void
process(void)
{
u_int msg_len;
u_int buf_len;
u_int consumed;
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u_char type;
const u_char *cp;
int r;
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buf_len = sshbuf_len(iqueue);
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if (buf_len < 5)
return; /* Incomplete message. */
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cp = sshbuf_ptr(iqueue);
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msg_len = get_u32(cp);
if (msg_len > MAX_MSG_LENGTH) {
error("bad message len %d", msg_len);
cleanup_exit(11);
}
if (buf_len < msg_len + 4)
return;
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if ((r = sshbuf_consume(iqueue, 4)) != 0 ||
(r = sshbuf_get_u8(iqueue, &type)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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buf_len -= 4;
switch (type) {
case SSH_AGENTC_ADD_SMARTCARD_KEY:
debug("process_add");
process_add();
break;
case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
debug("process_del");
process_del();
break;
case SSH2_AGENTC_SIGN_REQUEST:
debug("process_sign");
process_sign();
break;
default:
error("Unknown message %d", type);
break;
}
/* discard the remaining bytes from the current packet */
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if (buf_len < sshbuf_len(iqueue)) {
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error("iqueue grew unexpectedly");
cleanup_exit(255);
}
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consumed = buf_len - sshbuf_len(iqueue);
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if (msg_len < consumed) {
error("msg_len %d < consumed %d", msg_len, consumed);
cleanup_exit(255);
}
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if (msg_len > consumed) {
if ((r = sshbuf_consume(iqueue, msg_len - consumed)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
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}
void
cleanup_exit(int i)
{
/* XXX */
_exit(i);
}
int
main(int argc, char **argv)
{
fd_set *rset, *wset;
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int r, in, out, max, log_stderr = 0;
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ssize_t len, olen, set_size;
SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
LogLevel log_level = SYSLOG_LEVEL_ERROR;
char buf[4*4096];
extern char *__progname;
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ssh_malloc_init(); /* must be called before any mallocs */
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TAILQ_INIT(&pkcs11_keylist);
pkcs11_init(0);
seed_rng();
__progname = ssh_get_progname(argv[0]);
log_init(__progname, log_level, log_facility, log_stderr);
in = STDIN_FILENO;
out = STDOUT_FILENO;
max = 0;
if (in > max)
max = in;
if (out > max)
max = out;
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if ((iqueue = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((oqueue = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
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set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
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rset = xmalloc(set_size);
wset = xmalloc(set_size);
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for (;;) {
memset(rset, 0, set_size);
memset(wset, 0, set_size);
/*
* Ensure that we can read a full buffer and handle
* the worst-case length packet it can generate,
* otherwise apply backpressure by stopping reads.
*/
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if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 &&
(r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
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FD_SET(in, rset);
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else if (r != SSH_ERR_NO_BUFFER_SPACE)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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olen = sshbuf_len(oqueue);
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if (olen > 0)
FD_SET(out, wset);
if (select(max+1, rset, wset, NULL, NULL) < 0) {
if (errno == EINTR)
continue;
error("select: %s", strerror(errno));
cleanup_exit(2);
}
/* copy stdin to iqueue */
if (FD_ISSET(in, rset)) {
len = read(in, buf, sizeof buf);
if (len == 0) {
debug("read eof");
cleanup_exit(0);
} else if (len < 0) {
error("read: %s", strerror(errno));
cleanup_exit(1);
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} else if ((r = sshbuf_put(iqueue, buf, len)) != 0) {
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
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}
}
/* send oqueue to stdout */
if (FD_ISSET(out, wset)) {
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len = write(out, sshbuf_ptr(oqueue), olen);
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if (len < 0) {
error("write: %s", strerror(errno));
cleanup_exit(1);
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} else if ((r = sshbuf_consume(oqueue, len)) != 0) {
fatal("%s: buffer error: %s",
__func__, ssh_err(r));
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}
}
/*
* Process requests from client if we can fit the results
* into the output buffer, otherwise stop processing input
* and let the output queue drain.
*/
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if ((r = sshbuf_check_reserve(oqueue, MAX_MSG_LENGTH)) == 0)
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process();
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else if (r != SSH_ERR_NO_BUFFER_SPACE)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
}
#else /* ENABLE_PKCS11 */
int
main(int argc, char **argv)
{
extern char *__progname;
__progname = ssh_get_progname(argv[0]);
log_init(__progname, SYSLOG_LEVEL_ERROR, SYSLOG_FACILITY_AUTH, 0);
fatal("PKCS#11 support disabled at compile time");
}
#endif /* ENABLE_PKCS11 */